Coal Resource Recoverability
A Methodology

By Timothy J. Rohrbacher, Dale D. Teeters, Gerald L. Sullivan, and Lee M. Osmonson

U.S. Bureau of Mines Circular 9368

APPENDIX-GLOSSARY

Available coal resources.-Coal resources, minable by either surface or underground methods, that are unencumbered by land use, environmental, societal, regulatory, or technologic restrictions as applied within a specific State or region. In this study, available resources are derived by the following formula:

ORIGINAL COAL RESOURCES

-minus-

COAL MINED AND LOST-IN-MINING

-equals-

REMAINING COAL RESOURCES

-minus-

COAL RESTRICTED BY LAND USE CONSIDERATIONS

-minus-

COAL RESTRICTED BY TECHNOLOGIC CONSIDERATIONS

-equals-

AVAILABLE COAL RESOURCES

Bufferzone-The area surrounding a restrictive feature (mine, town, cemetery, oil or gas well, stream, etc.) in which mining is not permitted.


Coal availability/minable resource.-Refer to "Available coal resources."


Coal realization.-The conversion, economically, of coal into cash (i.e., the price for which coal sells).


Coal recoverability-Refer to "Recoverable coal."


Coal reserve.-Refer to "Reserve."


Coal resources.-Deposits of coal in the earth's crust in such amounts that physical extraction is currently or potentially feasible.


Coal seam.-A bed or stratum of coal.


Coal washinglpreparation-The process of cleaning (i.e., removing ash, etc.) or preparing run-of-mine coal to meet market specifications and to make it suitable for a particular use.


Compliance coal.-Coal that meets New-Source Performance Standards (NSPS), set forth by the EPA, for S02 emissions. This is coal that is in compliance without use of SO,-reduction processes, such as scrubbers. The current maximum limit from new-source coal-fired power plants is 1.2 lb of SO, per MBtu of heat input.


Deep coal resources.-Coal resources that would most probably be mined by underground mining methods.


Deep-mine barrierpillars.-Unmined coal left around the peripheries of active or abandoned underground mines due to mine-safety requirements. Also referred to as deepmine barriers.


Dilution.-The contamination of coal with barren rock from the roof and floor of an excavation.


Environmental restrictions.-Refer to "Land-use restrictions." Examples of these restrictions are cemeteries, towns and residences (social constraints), ground slopes <65%, major streams, and lakes (environimental constraints).


Floor rock.-The rock immediately underlying a coal bed. Where the coal section is overturned (inverted), the mining floor is actually above the coal bed, stratigraphicary.


Interburden.-The rock between two coal beds. When two potentially minable coal beds occur within a minimum acceptable distance above or below one another, one (often the thinner of the two) will not be mined.


Land use restrictions.-Constraints placed upon by societal policies to protect those surface features or entities that could be affected by mining. Since laws and regulations can be modified or repealed, the restrictions, including industrial and environmental restrictions, may change.


Lost-in-mining.-Unrecoverable coal remaining in the ground within a mine after all feasible extraction is completed. Includes coal that is (1) left to support mine roofs, (2) too thin or impure to mine, (3) unsafe for mining (e.g., bad roofs, faults, etc.), and (4) unmined around oil, gas, water, and disposal wells, shafts, conduits, haulageways, tunnels, and airways.


Mining methods.-The systems employed in the exploitation of coal seams and ore bodies. The method adopted depends on a large number of factors, the main ones being the quality, shape, size, and depth of the deposit, accessibifity, and capital available.


National Coal Resources Data System (NCRDS).-The U.S. Geological Survey computer system for storage, retrieval, and manipulation of stratigraphic, geochemica and coal resource-related data. The NCRDS stratigraphic data base contains information on more than 150,000 coal data points; the NCRDS geochemical data base includes analyses on nearly 13,000 coal samples. NCRDS graphics programs calculate and tabulate resources according to the specifications of the USGS coal-resources classification system. A national network of users and State cooperators is tied into NCRDS for interactive data retrieval manipulation, and coal resource assessment.


Original coal resources.-Coal resources, containing 33% or less ash, that lie under less than 6,000 ft of overburden and are either 14 or more inches thick (for anthracite and bituminous coal) or 30 or more inches thick (for subbituminous coal and lignite); the coal must e3dst in such form and amount that physical extraction is currently or potentiafly feasible.


Operating costs.-The sum of mining, beneficiation, and administration costs.


Outcrop.-That part of a coal bed or rock strata that appears at the surface (crops out).


Overburden.-Any material, consolidated or unconsolidated, that lies between a coal deposit and the surface.


Parfing.-A small layer of rock in a coal seam.


Perennial strearn.-A stream that flows continuously throughout the year.


Process losses.-Coal losses due to mining and washing.


Production.-The yield or output of a mine, metahurgical plant, or quarry.


Recoverable coal.-Coal that is, or can be, extracted from a coal bed during mining (See "Reserve").


Recovery.-The proportion, or percentage, of coal (or ore) that is mined from the original deposit.


Recovery factor.-The percentage of total estimated inplace coal that is potentially recoverable; or for a more precise determination, the percentage of total, estimated in-place coal that is actually mined. Recovery factors are generally about 50% for underground mining methods and from 80% to 90% for surface mining methods.


Reserve.-That part of a mineral deposit that could be economically and legally extracted or produced at the time of the reserve determination. When dealing with metalliferous minerals, reserves are customarily stated in terms of ore;' however, when other materials (coA oil shale, tar sands, limestone, etc.) are involved, a more appropriate term (such as "recoverable coal') may be substituted.


Restricted coal resources.-Coal resources that are determined to be umminable because of current land use or technologic restrictions.


Roof rock.-In underground mining, the rock immediately overlying a coal bed. Often the upper part of a coal bed is left un-mined to serve as a roof for the mining operations.


Strip ratio.-A numerical expression showing the proportional relationship of a unit amount of waste material to a similar unit amount of ore or mineral material; the waste material must be removed in order to gain access to the target material.


Surface coal resources.-Coal resources, usually within a few hundred feet of the surface, that would most probably be mined by surface mining methods.


Technologic restrictions.-Constraints, relating to economics and safety, placed upon mining by the state of technology or prescribed by law; the restrictions could change with advances in science or modifications in the law. In this report, geological factors are included as technologic restrictions.


Yield-Mine.-See "Recovery."

Yield-Plant.-Ratio of salable product produced, including impurities, to the total input of the mine to the plant.

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